Cleanup sceKernelCreateVpl() and add warns/errors.
Always use -1 for failed allocs in block allocator.

Before it used 0 and -1, confusing.
Change grain for memory to 8 bytes.

This should fix spurious warnings about AllocAt() when loading a game,
and matches the vpl tests.  It should allow slightly more free memory too.
Implement basic waiting for VPL allocation.

Always times out so far, though.